RISC-V: Add shorten_memrefs pass.

	gcc/
	* config.gcc:  Add riscv-shorten-memrefs.o to extra_objs for riscv.
	* config/riscv/riscv-passes.def: New file.
	* config/riscv/riscv-protos.h (make_pass_shorten_memrefs): Declare.
	* config/riscv/riscv-shorten-memrefs.c: New file.
	* config/riscv/riscv.c (tree-pass.h): New include.
	(riscv_compressed_reg_p): New Function
	(riscv_compressed_lw_offset_p): Likewise.
	(riscv_compressed_lw_address_p): Likewise.
	(riscv_shorten_lw_offset): Likewise.
	(riscv_legitimize_address): Attempt to convert base + large_offset
	to compressible new_base + small_offset.
	(riscv_address_cost): Make anticipated compressed load/stores
	cheaper for code size than uncompressed load/stores.
	(riscv_register_priority): Move compressed register check to
	riscv_compressed_reg_p.
	* config/riscv/riscv.h (C_S_BITS): Define.
	(CSW_MAX_OFFSET): Define.
	* config/riscv/riscv.opt (mshorten-memefs): New option.
	* config/riscv/t-riscv (riscv-shorten-memrefs.o): New rule.
	(PASSES_EXTRA): Add riscv-passes.def.
	* doc/invoke.texi: Document -mshorten-memrefs.

	* config/riscv/riscv.c (riscv_new_address_profitable_p): New function.
	(TARGET_NEW_ADDRESS_PROFITABLE_P): Define.
	* doc/tm.texi: Regenerate.
	* doc/tm.texi.in (TARGET_NEW_ADDRESS_PROFITABLE_P):  New hook.
	* sched-deps.c (attempt_change): Use old address if it is cheaper than
	new address.
	* target.def (new_address_profitable_p): New hook.
	* targhooks.c (default_new_address_profitable_p): New function.
	* targhooks.h (default_new_address_profitable_p): Declare.

	gcc/testsuite/
	* gcc.target/riscv/shorten-memrefs-1.c: New test.
	* gcc.target/riscv/shorten-memrefs-2.c: New test.
	* gcc.target/riscv/shorten-memrefs-3.c: New test.
	* gcc.target/riscv/shorten-memrefs-4.c: New test.
	* gcc.target/riscv/shorten-memrefs-5.c: New test.
	* gcc.target/riscv/shorten-memrefs-6.c: New test.
	* gcc.target/riscv/shorten-memrefs-7.c: New test.

1 files changed, 3 insertions, 0 deletions

diff --git a/gcc/sched-deps.c b/gcc/sched-deps.c
index 331af5f..1bc7507 100644
--- a/gcc/sched-deps.c
+++ b/gcc/sched-deps.c
@@ -4694,6 +4694,9 @@ attempt_change (struct mem_inc_info *mii, rtx new_addr)
   rtx mem = *mii->mem_loc;
   rtx new_mem;
 
+  if (!targetm.new_address_profitable_p (mem, mii->mem_insn, new_addr))
+    return NULL_RTX;
+
   /* Jump through a lot of hoops to keep the attributes up to date.  We
      do not want to call one of the change address variants that take
      an offset even though we know the offset in many cases.  These